Oneiromancy is a form of divination based upon dreams. It is a system of dream interpretation that uses dreams to predict the future. Dream divination was a common feature of Greek and Roman religion and literature of all genres.
Oneirocritic literature is the traditional literary format of dream interpretation. Artemidorus was a professional diviner and author known for the five volume Greek work Oneirocritica. According to Artemidorus, the material for his work was gathered from diviners during lengthy travels through Greece, Italy and Asia.
Artemidorus writes that dream interpretation is nothing other than the juxtaposition of similarities, but like other types of Greek divination, including astrology, celestial divination and pallomancy, Oneiromancy became exceedingly complex, with a given dream subject to a number of interpretations.
Dreams occur throughout the Bible as omens or messages from God. Jacob dreamed of a ladder to heaven and his son Joseph dreamed of his future success and interpreted the dreams of the Pharaoh of Egypt. The Magi are told in a dream to avoid Herod on their journey home, and Joseph, husband of Mary, was directed to flee to Egypt.